Fermented product based on an oat suspension

ABSTRACT

A fermented product selected from yogurt, yogurt drink, smothie, crème fraiche, sour cream, and spread is disclosed. The fermented product is based on an oat suspension essentially free from soy and dairy milk. Also disclosed is a process for preparing the product, and a starter culture useful in the process.

FIELD OF THE INVENTION

The present invention relates to a fermented product based on an oatsuspension free from soy, to a process for making the product, and to astarter culture useful in the process.

BACKGROUND OF THE INVENTION

Traditionally fermented dairy products are prepared from dairy milkcontaining selected amounts of milk fat which is preserved in therespective product. It is well known that consumption of milk fat mayincrease blood cholesterol levels with concomitant increased risk ofcoronary heart disease. From a health perspective it is thereforedesirable to keep the milk fat content of dairy products as low aspossible. There are also people who should abstain from consuming dairymilk and certain dairy milk products due to lactose intolerance orallergy to milk protein. In Europe about one million people are allergicto milk protein. Also the number of consumers who prefer a vegetarian orvegan diet is increasing. Furthermore various groups of people excludemilk and milk products from a meal due to religious reasons, as is thecase of kosher food. On the other hand, cow milk and products madetherefrom, from the standpoint of taste, consistency, nutritional value,etc., are desirable for many of these people which for one reason or theother have to avoid their use. Thus, as an alternative to cow milk andproducts made therefrom soy milk and products, such as soy yogurt, basedthereon have been developed and introduced on the market. Their use hashowever been hampered by many people suffering from milk allergy alsodeveloping allergy to soy protein.

Oats are acknowledged for their healthy properties. Oat protein is agood quality protein. Oats are rich in antioxidants and beta-glucan, awater-soluble dietary fibre, which exhibits cholesterol loweringproperties. An oat-based milk alternative with a mild taste and flavouris known in the art. It may replace dairy milk in a range ofapplications. This oat-based milk substitute resembles dairy milk withrespect to appearance and mouthfeel. It has a dry substance and sugarcontent similar to dairy milk but contains maltose and/or glucoseinstead of lactose. The oat-based milk alternative contains varioussugars that are products of enzyme hydrolysis. By introducing this milkalternative in various foods the consumer's intake of dietary fibre isincreased with concomitant health benefits, whereas the intake of milkfat is eliminated.

OBJECTS OF THE INVENTION

It is a prime object of the invention to provide a fermented non-dairyproduct low in protein and free from soy and dairy milk.

Thus, in particular, it is an object of the invention to provide anon-dairy yogurt suitable as a low-protein substitute for thecorresponding dairy product.

Thus, in particular, it is an object of the invention to provide anon-dairy crème fraiche product suitable as a low-protein substitute ofthe corresponding dairy product.

Thus, in particular, it is an object of the invention to provide anon-dairy spread product suitable as a low-protein substitute of thecorresponding dairy product.

Thus, in particular, it is an object of the invention to provide anon-dairy yogurt drink or smoothie product suitable as a low-proteinsubstitute of the corresponding dairy product.

It is a further object of the invention to provide a non-dairy productof the aforementioned kind rich in soluble β-glucan fibre.

Additional objects of the invention will be evident from the followingdescription of the invention and preferred embodiments thereof, and ofthe appended claims.

SUMMARY OF THE INVENTION

According to the present invention is disclosed a fermented productbased on an oat suspension essentially free from soy and dairy milk,such as the suspension disclosed in U.S. Pat. No. 5,686,123, which ishereby incorporated by reference. The oat suspension has a smoothtexture and mild taste; it has particularly smooth texture and mildtaste when the insoluble fibre has been removed. Therefore thecorresponding fermented product has an inherent smooth mouthfeel.

For the preparation of a fermented product according to the invention itis preferred to use an oat base in form of an aqueous oat suspensionhaving a dry matter content of about 10% or a concentrated or dried formthereof, the oat base dry matter containing from about 10 to 50% byweight of monosaccharides, in particular maltose or a mixture of maltoseand glucose, and from 30 to 80% by weight of maltodextrin. It ispreferred for the oat base dry matter to contain from 5% by weight to15% by weight of protein.

For the production of a fermented product according the invention havingconsistency properties similar to yogurt is preferred the use of an oatsuspension containing about 20% of dry weight of maltose, the remainderof carbohydrates substantially consisting of maltodextrin of varyingmolecular weight. A suitable oat base material for making theyogurt-like fermented product of the invention is, for instance,Adavena® M20 marketed by Ceba AB, Lund, Sweden. The yogurt-like productof the invention has a consistency similar to that of natural yogurt inspite of having a low protein content, such as a protein content below20% of dry weight, more preferred below 12% of dry weight. Thisconsistency is achieved without taking recourse to the addition ofgelatin or modified starch or other consistency moderating additives. Itis thus preferred for the yogurt-like product of the invention to besubstantially free from consistency moderating additives.

For the production of a fermented product according the invention havingconsistency properties similar to crème fraiche or sour cream ispreferred the use of an oat suspension containing about 20% of dryweight of maltose, the remainder substantially consisting ofmaltodextrin capable of forming a gel. A suitable oat base material formaking the crème fraiche-like fermented product of the invention is, forinstance, Adavena M20 marketed by Ceba AB, Lund, Sweden. Despite thedifferences in protein content between dairy milk and the oat base usedin the invention, fermented oat products such as the aforementionedcrème fraiche-like product can be prepared.

For making the yogurt smoothie fermented product according the inventionhaving consistency properties similar to a yogurt drink or smoothie ispreferred the use of an oat suspension containing about 40% of dryweight of maltose, the remainder of carbohydrates substantiallyconsisting of maltodextrin of varying molecular weight. A suitable oatbase material for making the crème fraiche-like fermented product of theinvention is, for instance, Adavena M40 marketed by Ceba AB, Lund,Sweden.

For making the spread-like fermented product according the invention(referred to as “spread” in the following) having consistency propertiessimilar to a spread is preferred the use of an oat suspension containingabout 20% of dry weight of glucose, the remainder of carbohydratessubstantially consisting of maltodextrin of varying molecular weight. Asuitable oat base material for making the yogurt-like fermented productof the invention is, for instance, Adavena® G20 marketed by Ceba AB,Lund, Sweden manufacturing a range of Adavena® oat base products. Theyogurt-like product of the invention has a consistency similar to thatof natural yogurt in spite of having a low protein content, such as aprotein content below 20% of dry weight, more preferred below 12% of dryweight. This consistency is achieved without taking recourse to theaddition of gelatin or modified starch or other consistency moderatingadditives. It is thus preferred for the yogurt-like product of theinvention to be substantially free from consistency moderatingadditives.

According to a first preferred aspect of the invention the oat milksuspension is fermented with lactic acid bacteria. Thereby a thickenedproduct of lower pH is obtained. It is preferred to use a conventionalyogurt starter culture, such as one comprising Lactobacillus delbruckiisubsp. bulgaricus and Streptococcus thermophilus, complemented withLactobacillus acidophilus. Thereby a more acidic product is obtained,since Lactobacillus acidophilus ferments maltose better thanconventional yogurt starter cultures. It is also preferred to use astarter culture devoid of such hydrolytic activity that would reduce thefibre content of the oat product, such as a starter culture havingβ-glucanase activity. The reason for the advantageous effect obtained bycomplementation with L. acidophilus may be due to the buffer capacity ofthe oat base being much lower than that of dairy milk due to its lowprotein content. When the oat base is fermented the pH decreases ratherquickly. Thereby the growth of L. bulgaricus and S. thermophilus isincreasingly inhibited while that of L. acidophilus is only moderatelyaffected or not affected at all. This property is important since ithelps the taste and aroma typical of yogurt to develop.

The thickening of dairy yogurt is due to the coagulation of milkprotein. The protein in dairy yogurt supports the formation of a stronggel by calcium caseinate forming a characteristic network in an acidicenvironment. Soy protein exhibits similar thickening properties. Theprotein content of oat-based milk alternative is low compared with theprotein content of dairy milk and milk-like soy products. The lack of astrong protein network in the oat product having consistencysubstantially different from that of its soy or dairy counterparts.

According to a second preferred aspect of the invention,exopolysaccharide (EPS)-producing microorganisms (see, for instance: ARicciardi and F Clementi, Exopolysaccharides from lactic acid bacteria:structure, production and technological applications, Ital J Food Sci 12(2000) 23–45) are included in the inoculum for improving the consistencyof the fermented oat product. Wild type microorganisms or microorganismsthat contain the gene for production of EPS may be used. Theseextra-cellular polysaccharides have a synergistic effect in combinationwith the maltodextrin and beta-glucan of the oat-based milk alternativethereby yielding a desirable product texture. While their additionincreases both the viscosity and the elasticity of the product, theincrease in elasticity is considerably more pronounced. An addition ofEPS producing microorganisms is particularly preferred in the productionof spreadable products according to the invention. The EPS-producingmicroorganisms of the invention are preferably added in an amount offrom 10 to 50% by weight, and even up to 80%, such as by substitutingthe state-of-the-art L. delbruckii subsp. bulgaricus variety by from 10to 50% by weight, and even up to 80% by weight, of L. delbruckii subsp.bulgaricus NCFB 2772.

The exopolysaccharides may be of a sort readily digestible by humans ormay constitute dietary fibre, such as microbial beta-glucan. The fibrecontent of the yogurt-like product is thus enhanced with no extraaddition of fibre.

According to a third preferred aspect of the invention the colour of thefermented product is improved by the method of the invention. While theoat base has grayish tint typical for suspensions of cereal material,the fermented product of the invention has a white appearance similar tothat of the corresponding dairy milk-derived products.

According to fourth preferred aspect of the invention calcium may beoptionally added as calcium hydrogen phosphate CaHPO₄.2H₂O or Ca₃(PO₄)₂.A dosage of 0.5% by weight of dry oat base corresponds to theconcentration of calcium in dairy milk and is preferred.

According to a fifth preferred aspect of the invention the productsaccording to the invention contain more than 0.3% by weight of solubleβ-glucan, in particular more than 0.5% of soluble β-glucan.

The fermented product can have a protein content of below 4% by weight,such as from 0.5% to 2.0% by weight.

Further preferred aspects and advantages of the invention are disclosedin the appended claims and in the following detailed description of theinvention referencing to a number of illustrative but not limitingexamples.

PREFERRED EMBODIMENTS OF THE INVENTION

Oat-based materials in general. Commercial grade Adavena® products wereused as oat base. They are aqueous suspensions having a dry mattercontend of about 10%, similar to cow milk; they can be concentratedwithout difficulty by evaporation to a dry matter content of about 25%or dried to a powder. While the dry matter protein content of cow milkis from about 32% by weight to about 36% by weight, the dry matterprotein content of the oat-based Adavena® products is from about 11% byweight to about 14% by weight. On the other hand protein in oat-basedproducts like the Adavena® line is better balanced in respect tocarbohydrates and fat than the protein in milk. This is not true for allcereals; rice milk, for instance, is poor in protein.

EXAMPLE 1 Non-dairy Yogurt A

Ingredients:

Oatbase: Adavena® M20, (CEBA AB, Lund, Sweden; dry matter containing 20%by weight of maltose), adjusted to a dry matter content 14–16%.

Starter culture: An ordinary yogurt starter culture of Lactobacillusbulgaricus and Streptococcus thermophilus complemented withLactobacillus acidophilus. Add starter culture in amounts as forordinary milk yogurt, 0.02% by weight of starter culture from aconcentrated frozen pellet, such as comprised to 75% by weight ofordinary starter culture (L. bulgaricus and S. thermophilus), and to 25%by weight of L. acidophilus.

Process:

-   -   1. Weigh Adavena® M20 powder;    -   2. Weigh the amount of water needed to reach a dry matter        content of 14% by weight when added to the M20 Adavena powder;    -   3. Add a small amount of the water to the M20 powder and mix to        a homogenous slurry;    -   4. Add the remaining water to the M20 slurry;    -   5. Heat the slurry to 90° C.; hold this temperature for 6        minutes to pasteurize the product;    -   6. Cool to incubation temperature, 43° C.;    -   7. Inoculate with starter culture; incubate at 43° C. for 16        hours;    -   8. Cool below 8° C. for storage.

The viscosity of the M20 oat base (at 14% by weight of dry solids) was80,000 cP. The viscosity of the fermented oat base was 120,000 cP. Themeasurement was performed at 4° C. with a Brookfield viscosimeter at ashear rate of 0.3 rpm to protect the product structure againstdeformation due to shear stress.

The fermented product has a fairly low pH value (about 3.9), but afteradding flavor its taste is only slightly sour. The fermentation can beinterrupted at a higher pH value if desired. The fermented oat base maybe flavoured with, for instance, vanilla, cocoa, hazelnut, caramel orwith different kinds of jam, such as mango, pineapple, peach, apple,etc.; by definition jam is a food made by cooking fruit with a largeamount of sugar).

EXAMPLE 2 Non-dairy Yogurt B

Ingredients and process as in Example A except for substituting 30% byweight of L. delbruckii subsp. bulgaricus variety used in Example 1 bythe same amount of L. delbruckii subsp. bulgaricus NCFB 2772 obtainedfrom the National Culture Collection of Food Bacteria, Aberdeen,Scotland. The texture of the yogurt product is determined as elasticity(or ropiness) by measurement with an Instron 4442 (Instron Ltd., HighWycombe, Buckinghamshire, UK) using a platen with a diameter of 3.8 cmand a speed of 100 cm/min. The elasticity value for a product obtainedby using a traditional starter culture lacking exopolysaccharideproducing microorganisms was found to be about 2 cm/min whereas that ofa product obtained by use of a corresponding starter culture comprisingof L. delbruckii subsp. bulgaricus NCFB 2772 was found to be about 6cm/min.

EXAMPLE 3 Non-dairy Spread

Adavena® G20 oat base suspension (17% by weight of dry solids; drymatter containing 20% of glucose) was fermented with the starter cultureof Example 2 for the preparation of a spread. The viscosity of thespread was in the order of 1,000,000. Elasticity measurement with anInstron 4442 instrument showed an elasticity increase from about 2cm/min to about 7 cm/min in case of the use of a starter culturecomprising L. delbruckii subsp. bulgaricus NCFB 2772. The viscosity inthe spread was in the order of 1,000,000 cP at 4° C. and 0.3 rpm.

EXAMPLE 4 Non-dairy Smoothie

Adavena® M40 oat base suspension (dry solids content 7–15%; dry solidscontaining 40% by weight of maltose). Starter culture as in Example 1.

Process:

-   -   1. Weigh Adavena® M40 powder;    -   2. Weigh the amount of water needed to reach a dry matter        content of 10% M40;    -   3. Add a small amount of the water to the M40 powder and mix to        a homogeneous slurry;    -   4. Add the remaining water to the M40 slurry;    -   5. Heat the slurry to 90° C.; hold this temperature for 6        minutes to pasteurize the product;    -   6. Cool to incubation temperature, 43° C.;    -   7. Inoculate with starter culture; incubate at 43° C. for 16        hours;    -   8. Cool below 8° C. for storage.

Alternatively a commercial liquid Adavena® M20 oat base suspensionhaving a dry matter content of from 7% to 12 can be used. When usingsuch a ready-made suspension steps 1–4 of the process can be dispensedwith. The suspension used directly for step 5. The alternative of usinga commercial liquid Adavena® oat base suspension of appropriate kind asa raw material is also applicable to the other Examples describedherein.

The fermented product will reach a fairly low pH value of about 4.0 butafter adding flavour the taste will be only slightly sour. Thefermentation can be interrupted at a higher pH value if desired. Whilethe viscosity of the non-diary smoothie was about 30,000 cP at at 4° C.and 0.3 rpm.

EXAMPLE 5 Non-dairy Crème Fraiche or Sour Cream

Prepared by a modification of Example 1 from Adavena® M20 oat basesuspension (7–12% of weight dry matter) but using a crème fraicheculture and incubating at an optimal temperature for this culture, 36°C. The starter culture, 0.02% by weight of concentrated frozen pellet,comprised equal amounts of a crème fraiche culture (consisting ofLactococcus lactis subsp. diacetylactis and Leuconostoc mesenteroidessubsp. cremoris; manufactured by Chr. Hansen AB, Flygfä. 11, Göteborg,Sweden), and Lactobacillus acidophilus. The viscosity of the non-dairycrème fraiche product or sour cream product of the invention was in theorder of 1,000,000 cP but difficult to measure. If desired anEPS-producing microorganism like L. delbruckii subsp. bulgaricus NCFB2772 can be added to the starter culture or later to increase theviscosity of the product.

1. A process for preparing a fermented product selected from the groupconsisting of yogurt, yogurt drink, smoothie, crème fraiche, sour creamand spread based on an oat suspension free from soy and dairy milk, theprocess comprising: (a) providing an oat base in form of an aqueous oatsuspension free from soy and dairy milk and having a dry matter contentof 7–17%, the oat base dry matter comprising from 10 to 50% by weight ofmaltose or a mixture of maltose and glucose, from 30 to 80% by weight ofmaltodextrin and from 5% to 15% by weight of protein; (b) heating thesuspension to a first temperature above 80° C.; (c) holding thesuspension at this first temperature for a time period sufficient topasteurize the product; (d) cooling the suspension to a secondtemperature of from about 30° C. to about 50° C.; (e) inoculating thesuspension with a starter culture at the second temperature; (f)incubating the suspension at the second temperature for a time periodsufficient to ferment the suspension to the desired fermented product;and (g) cooling the fermented product so obtained to a temperature below8° C. for storage; wherein the oat suspension is optionally agitated inone or more of the (b) to (g) to prevent it from settling.
 2. Theprocess of claim 1, wherein the first temperature is about 90° C.
 3. Theprocess of claim 1, wherein the second temperature is about 43° C. 4.The process of claim 1, wherein the starter culture comprisesLactobacillus delbruckii subsp. blugaricus and Streptococcusthermophilus.
 5. The process of claim 1, wherein the starter culturecomprises Lactobacillus acidophilus.
 6. The process of claim 1, whereinthe starter culture comprises an exopolysaccharide (EPS) producingmicroorganism.
 7. The process of claim 6, wherein the EPS producingmicroorganism is L. delbruckii subsp. bulgaricus NCFB
 2772. 8. Theprocess of claim 6, further comprising at least one of Lactobacillusbulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus,Lactococcus lactis subsp. diacetylactis, Leuconostoc mesenteroidessubsp. cremoris.
 9. The process of claim 8, wherein the EPS-producingorganism is L. delbruckii subsp. Bulgaricus NCFB
 2772. 10. The processof claim 1, wherein the dry matter protein content of the oat base isless than 12% by weight.
 11. The process of claim 10, wherein the drymatter maltose content is about 20–40% by weight.
 12. A fermentedproduct selected from the group consisting of yogurt, yogurt drink,smoothie, crème fraiche, sour cream and spread, prepared by the processof claim
 1. 13. The fermented product of claim 12 comprising calciumhydrogen phosphate, calcium phosphate or both, in an amount of about0.5% by weight of dry oat base.
 14. The fermented product of claim 12comprising more than 0.3% by weight of soluble β-glucan.
 15. Thefermented product of claim 14, comprising more than 0.5% of solubleβ-glucan.
 16. A yogurt of claim 12, wherein the dry matter content ofsaid aqueous oat suspension is 14–16% by weight, and contains about 20%of maltose based on dry weight.
 17. The yogurt product of claim 12, freefrom consistency modifying additives.
 18. The yogurt product of claim17, having a viscosity of about 120,000 cP measured at 4° C. with aBrookfield viscosimeter at a shear rate of 0.3 rpm.
 19. A yogurt drinkor smoothie product of claim 12, wherein the dry matter content of saidaqueous oat suspension is 7–15% by weight, and contains about 40% ofmaltose based on dry weight.
 20. A yogurt drink or smoothie product ofclaim 12, free from consistency modifying additives.
 21. A smoothie ofclaim 12, having viscosity of about 30,000 cP measured at 4° C. with aBrookfield viscosimeter at a shear rate of 0.3 rpm.
 22. A crème fraicheor sour cream product of claim 12, wherein the dry matter content ofsaid aqueous oat suspension is 7–12% by weight, prepared from an oatbase containing about 20% of maltose based on dry weight.
 23. A crèmefraiche or sour cream product of claim 12, free from consistencymodifying additives.
 24. A spread product of claim 12, wherein the drymatter content of said aqueous oat suspension is 17% by weight, preparedfrom an oat base containing maltose and glucose in which the glucose isabout 20% based on dry weight.
 25. A spread product of claim 12, freefrom consistency modifying additives and having a viscosity above500,000 cps measured at 4° C. with a Brookfield viscosimeter at a shearrate of 0.3 rpm.
 26. The fermented product of claim 12, having a proteincontent of below 4% by weight.
 27. The fermented product of claim 15,having a protein content of from 0.5% to 2.0% by weight.
 28. A processfor preparing a fermented product selected from the group consisting ofyogurt, yogurt drink, smoothie, crème fraiche, sour cream and spreadbased on an oat suspension free from soy and dairy milk, the processcomprising: (a) providing an oat base in form consisting of an aqueousoat suspension free from soy and dairy milk and having a dry mattercontent of 7–17%, the oat base dry matter comprising from 10 to 50% byweight of maltose or a mixture of maltose and glucose, from 30 to 80% byweight of maltodextrin and from 5% to 15% by weight of protein; (b)heating the suspension to a first temperature above 80° C.; (c) holdingthe suspension at this first temperature for a time period sufficient topasteurize the product; (d) cooling the suspension to a secondtemperature of from about 30° C. to about 50° C.; (e) inoculating thesuspension with a starter culture at the second temperature; (f)incubating the suspension at the second temperature for a time periodsufficient to ferment the suspension to the desired fermented product;and (g) cooling the fermented product so obtained to a temperature below8° C. for storage; wherein the oat suspension is optionally agitated inone or more of the (b) to (g) to prevent it from settling.
 29. A processfor preparing a fermented product selected from the group consisting ofyogurt, yogurt drink, smoothie, crème fraiche, sour cream and spreadbased on an oat suspension free from soy and dairy milk, the processconsisting of: (a) providing an oat base in form of an aqueous oatsuspension free from soy and dairy milk and having a dry matter contentof 7–17%, the oat base dry matter comprising from 10 to 50% by weight ofmaltose or a mixture of maltose and glucose, from 30 to 80% by weight ofmaltodextrin and from 5% to 15% by weight of protein; (b) heating thesuspension to a first temperature above 80° C.; (c) holding thesuspension at this first temperature for a time period sufficient topasteurize the product; (d) cooling the suspension to a secondtemperature of from about 30° C. to about 50° C.; (e) inoculating thesuspension with a starter culture at the second temperature; (f)incubating the suspension at the second temperature for a time periodsufficient to ferment the suspension to the desired fermented product;and (g) cooling the fermented product so obtained to a temperature below8° C. for storage; wherein the oat suspension is optionally agitated inone or more of the (b) to (g) to prevent it from settling.